Head Injury. Brain was injured at all.

While outside, I was in the woods while crossing a very small and muddy stream when the unsuspectingly flimsy fallen tree I was using to get across snapped. I fell on my feet on the opposite bank barely out of the stream and a split second later, the tree snapped again and fell directly on my head. It was around 5 inches in diameter and around 4-5 feet long when it fell. After it hit my head, I had a moderate pain on my head, but it wasn't much like a headache, just a sharp pain. After feeling around the top of my head for a while, I found that it was bleeding to the extent my hair was matted with it and my hands were half surfaced with blood. In addition, I had depressing thoughts, such as I wouldn't mind if I died right now, which was extremely surprising. It is still bleeding a little now after 3 hours. I just wanted to know if my brain was injured at all. Thank you so much!